1. Field
The present disclosure generally relates to methods and apparatus for determining the quality of a communication link, and more particularly to determining quality of service of a communication link or path having wireless or wired network transmission of real time traffic, such as voice data.
2. Background
In communication systems, the utilization of applications using real time traffic, such as end-to-end Voice over IP (VoIP) calls, is ever increasing. The routing between end points involved in such applications will typically access an IP network (e.g., the Internet) through any one or a combination of a number of different communication network technologies. Examples of types of network technologies used may include Wireless Local Area Networks (WLAN) such as Wi-Fi (IEEE Std. 802.11), Cellular Networks such as 1X-EVDO, High Speed Packet Access (HSPA), Wireless Wide Area Networks (WWAN) such as WiMAX (IEEE 802.16), femtocells, and still other various known and to-be-defined network technologies. Accordingly, real time traffic may be exchanged over numerous networks in the routing between the end points. For example, in an end-to-end VoIP call between a user A and a user B in a residential setting, the VoIP packets can potentially traverse user A's Wi-Fi access network, user A's DSL or cable broadband network, an IP core network, user B's DSL or cable broadband network, and user B's Wi-Fi access network.
In the case of VoIP traffic, for example, the VoIP packets that carry voice data must traverse the overall network within a maximum allowable delay constraint to achieve an acceptable quality of service (QoS). Because VoIP packets traverse so many potentially disparate networks between end points of a voice call, and because broadband networks, such as the Internet, typically carry a myriad of types of data packets, the monitoring of the QoS for delay-sensitive voice packets within each network link is not generally feasible. Accordingly, the VoIP QoS is more easily monitored by one or both of the devices at the end points of a voice call (e.g., terminals such as a mobile phone or a computer), since such devices are affected by QoS degradation occurring anywhere within the networks utilized to route the call.
Although quality determination metrics are available in certain networks used to route a voice call, such as in the Wi-Fi Medium Access Control (MAC) Management Information Base (MIB), such metrics are not effective in determining the resulting path quality for all situations. Consider, for example, a VoIP call occurring in a Voice over Wireless Local Area Network (VoWLAN) in a residential environment. In order to determine QoS, at least four links need to be monitored: the downlink from a LAN access point (AP) to a communication terminal, the uplink from the communication terminal to the AP, the downlink from the call termination equipment (e.g., a media server at a VoIP service provider's network) to the AP, through the Internet backbone and the Cable/DSL backhaul, and an uplink from the AP to the call termination equipment through the Cable/DSL backhaul and the Internet backbone. It is possible for the communication terminal to monitor at least the first two of these links using locally visible events such as packet losses or signal strength, for example. However, there is no known mechanism that provides monitoring of the quality of the uplink and downlink between an AP and termination equipment. Accordingly, there is a need for a mechanism to measure or determine the QoS at a communication terminal or AP for at least a portion of a communication path from the AP to termination equipment, particularly paths carrying real time traffic.